I want to count redis big key,so I did this redis-cli --bigkeys， but I found a key is empty ,it is a list but there are 102360 items
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The empty string is a valid name for a key in Redis. You can access it like so:
redis-cli> TYPE ""
list
Related
For example, I have stored a value under some keys in redis with prefix doc:
doc:office:room_1
doc:office:room_2
doc:reception
Let's say I want to find key prefix doc:office:
How can I fastly search keys by prefix beside KEYS, SCAN command?
I have checked Redis Search, but it works only on fields not on the keys itself.
Can I add index keys somehow?
You could manage an index yourself. For example, you could have a Set called doc:office. Whenever you add or remove a key that starts with doc:office, you could add or remove that string from the Set. Then, if you need all the keys with that prefix, just get the members of the Set.
Like this:
> SET doc:office:room_1 data
> SADD doc:office doc:office:room_1
> SET doc:office:room_2 moardata
> SADD doc:office doc:office:room_2
> SMEMBERS doc:office
1) doc:office:room_1
2) doc:office:room_2
I have checked following, but didn't work.
https://redis.io/commands/keys
KEYS Room:*
1) "Room:120"
2) "Room:121"
3) "Room:122"
Following is the redis key/values (HMSET)
Room:120 [SocketId:mOQDJusPjDTBN5L-AAAC,TimeStamp:10-10-2017 12:10:00 AM]
Room:121 ....
Room:122 ....
...
Need to search as Room:* SocketId:mOQDJusPjDTBN5L-AAAC
How can I search for SocketId in the collection ?
Need to search with:
mOQDJusPjDTBN5L-AAAC
The question is not so clear
as u mentioned hmset i am assuming that you are using hashes to store your data.
As per your data,
'room120' should be the key, 'socketId' should be the field and 'mOQDJusPjDTBN5L-AAAC' should be the value.
so in order to search for socketId you can use hscan,where hscan iterates through the field of a particular key.https://redis.io/commands/scan
in case if you are just using key/value storage i.e
'socketId' being the key ,'mOQDJusPjDTBN5L-AAAC' being the value.
here u can just use the command Keys *socket*to search for the key socketId
I am using std::map to add values
std::map<CString,int>
the follwing is the list of items to be inserted as Key
X_1O1
X_101_A
X_70
X_67
I was expecting a sorted map with
X_67
X_70
X_101
X_101_A
but i am getting the result as
X_101
X_101_A
X_67
X_70
is there a way that I can sort the keys properly in the map?
I'm iterating through data and dumping some to a Redis DB. Here's an example:
hmset id:1 username "bsmith1" department "accounting"
How can I increment the unique ID on the fly and then use that during the next hmset command? This seems like an obvious ask but I can't quite find the answer.
Use another key, a String, for storing the last ID. Before calling HMSET, call INCR on that key to obtain the next ID. Wrap the two commands in a MULTI/EXEC block or a Lua script to ensure the atomicity of the transaction.
Like Itamar mentions you can store your index/counter in a separate key. In this example I've chosen the name index for that key.
Python 3
KEY_INDEX = 'index'
r = redis.from_url(host)
def store_user(user):
r.incr(KEY_INDEX, 1) # If key doesn't exist it will get created
index = r.get(KEY_INDEX).decode('utf-8') # Decode from byte to string
int_index = int(index) # Convert from string to int
result = r.set('user::%d' % int_index, user)
...
Note that user::<index> is an arbitrary key chosen by me. You can use whatever you want.
If you have multiple machines writing to the same DB you probably want to use pipelines.
In Redis, to store an array of objects we should use hash for the object and add its key to a list:
HMSET concept:unique_id name "concept"
...
LPUSH concepts concept:unique_id
...
I want to retrieve all hash values (or objects) in the list, but the list contains only hash keys so a two step command is necessary, right? This is how I'm doing in python:
def get_concepts():
list = r.lrange("concepts", 0, -1)
pipe = r.pipeline()
for key in list:
pipe.hgetall(key)
pipe.execute()
Is it necessary to iterate and fetch each individual item? Can it be more optimized?
You can use the SORT command to do this:
SORT concepts BY nosort GET concept:*->name GET concept:*->some_key
Where * will expand to each item in the list.
Add LIMIT offset count for pagination.
Note that you have to enumerate each field in the hash (each field you want to fetch).
Another option is to use the new (in redis 2.6) EVAL command to execute a Lua script in the redis server, which could do what you are suggesting, but server side.